[Analysis of serum 25-hydroxyvitamin D₃ levels and prognosis in patients with amyotrophic lateral sclerosis].

<b>Objective:</b> To evaluate serum 25-hydroxyvitamin D₃ [25(OH)D₃] as a potential biomarker for amyotrophic lateral sclerosis (ALS) severity and to identify risk factors influencing ALS prognosis. <b>Methods:</b> This study included 217 ALS patients hospitalized at the Department of Neurology, First Medical Center, Chinese PLA General Hospital, between October 2018 and October 2021, who met the revised El Escorial diagnostic criteria. A cross-sectional analysis assessed differences in clinical indicators-including the ALS Functional Rating Scale-Revised (ALSFRS-R) and forced vital capacity percentage (FVC%)-across different serum 25(OH)D₃ levels. The correlation between 25(OH)D₃ levels and individual ALSFRS-R components was also examined. Conduct a prospective cohort study to identify independent risk factors affecting the survival time of ALS patients. <b>Results:</b> Among three groups categorized by serum 25(OH)D₃ levels, there were significant differences in the proportion of males (<i>χ</i>²=10.51, <i>P</i><0.05). Serum 25(OH)D₃ levels correlated positively with lower limb function scores in the ALSFRS-R (<i>r</i>=0.05, <i>P</i><0.05), but they were not identified as an independent risk factor for survival (<i>HR</i>=0.98, 95%<i>CI</i> 0.93-1.04, <i>P</i>>0.05). In contrast, delayed diagnosis(<i>HR</i>=0.94, 95%<i>CI</i> 0.89-0.99, <i>P</i><0.05) and reduced FVC%(<i>HR</i>=0.94, 95%<i>CI</i> 0.97-0.99, <i>P</i><0.05) were independent predictors of shorter survival. <b>Conclusion:</b> Serum 25(OH)D₃ levels differ by gender distribution and may be linked to better lower limb function in ALS patients. However, their role in prolonging survival remains uncertain.